1. Field of the Invention
Embodiments of the present invention relates to security inspection equipment, and in particular to a photoelectric switch for detection of an object, used in security inspection equipment, and a method for operating the photoelectric switch.
2. Description of the Related Art
In conventional security inspection equipment, photoelectric switch for detection of an object is used to judge if an object exists in a detection area or not. Generally, there is one-to-one correspondence between the transmitter tubes and the receiver tubes in conventional photoelectric switch. As a result, more is the transmitter tubes, more is the receiver tubes. This causes numerous components and bulky size. Furthermore, due to differences in performance among these transmitter tubes, these receiving signals have a bad consistency, which adversely affects performance of the subsequent amplification circuit, thereby degrading performance of the whole system.
Moreover, as to algorithm applied in operations of the conventional photoelectric switch, these photoelectric receiving operations are running in binary, that is, a fixed threshold is predefined and on/off of the blocked state would be changed once it goes beyond the threshold. However, in practical application, transmissions and receptions of infrared lights are highly negatively affected by environmental lights, such as sunlight and lamplight, and correspondingly false operation is easy to appear when the environment is not good.
In addition, in the design of conventional photoelectric switch, due to fixed intervals among plural transmitter tubes, a resolution for detection is non-adjustable